Safety device for delayed action fuze



Sept. 4, 1962 H. L. THWAITES ETAL 3,052,187

SAFETY DEVICE FOR DELAYED ACTION FUZE Filed Dec. 22, 1944 Fig. 2. 14 J7Hernia-n, L. 77Lwaz'1es E] nmm tow G tl'o rump United States Patent3,052,187 SAFETY DEVICE FOR DELAYED ACTION FUZE Herman L. Thwaites,Clark Township, and Garland H. B. Davis, Elizabeth, N.J., assignors tothe United States of America as represented by the Secretary of WarFiled Dec. 22, 1944, Ser. No. 569,490 9 Claims. (Cl. 10282) Thisinvention relates to a safety device for a delayed action fuze and moreparticularly to a safety device capable of self-arming when placed incontact with a liquid.

An object of this invention is to provide a self-arming safety devicefor a grenade incorporating a time delay fuze such as is described andclaimed in the copending application Ser. No. 569,401, filed December22, 1944, of Herman L. Thwaites and George L. Matheson.

A further object of the invention is to provide a selfarming safetydevice that will supplement a manually operated safety device to renderthe time delay fuze safe when the manual safety device has been removed.

Other objects and advantages of the invention will appear from thefollowing description and the accompanying drawings in which:

FIG. 1 is a side view of a grenade incorporating the invention;

FIG. 2 is atop view of a grenade incorporating the invention; and I FIG.3 is a vertical section taken along the lines 33 of FIG. 2.

Referring to the drawings in detail, the grenade consists of a chargecup 14 threadedly engaged with a fuze case 5 by means of a screw cap 13and a primer holder 15. The charge cup 14 contains a plurality of TNTpellets 19 having a central hole through which extends a detonator 18.The TNT pellets 19 are spaced from the Side walls and the bottom of thecup 14, and this space is filled with magnesium powder 2% The magnesiumpowder preferably comprises a mixture of gradient size particles.

Within the fuze case 5 is contained 'a firing pin 11 threadably engagedwith a firing pin nut which is urged to the firing position toward aprimer 16 by a spring 9. The end of the firing pin 11 opposite theprimer 16 is provided with outwardly tapered shoulders abutting againstcorresponding inwardly tapered shoulders of a split washer 8. The splitwasher 8 is held in the position shown in the drawing by a retainingring 6. It will be evident that when the retaining ring 6 is movedupwardly from around the split washer 8, the split washer is caused toseparate because of the action of spring 9, and the firing pin 11 isdriven against the primer 16.

The retaining ring 6 is secured to the shank of a perforated plunger 2by means of a brass screw 7. Between the perforated under-shoulder ofthe plunger 2 and a shoulder of the fuze case 5 are positioned abakelite washer 4 and two rubber discs 3. The rubber discs 3 arepositioned between the Bakelite washed 4 and the perforated shoulder ofthe plunger 2 so that when the rubber discs swell on immersion in thegasoline or other liquid hydrocarbon they will move the perforatedplunger 2 upwardly thus withdrawing the retaining ring 6 from around thesplit washer 8.

Adjacent the upper portion of the fuze case 5 are provided two holes forreceiving a cotter pin and pull ring assembly 1. When the cotter pin isin position, movement of the perforated plunger 2 in an upward directionis prevented. This pull ring and cotter pin assembly 1 thereforeprovides a manually operable safety to insure against premature firingof the device.

A self-arming safety device is provided which renders the fuze safeafter the cotter pin and pull ring assembly have been removed manually.This self-arming safety consists of a rubber disc 17 compressed withinthe bore of the fuze case 5 at its open end directly above theperforated plunger 2. The rubber disc 17 is sprung into position andserves to hold the perforated plunger 2 firmly in position after thepull ring and cotter pin have been withdrawn. Thus accidentaldisplacement of the perforated plunger 2 and consequent release of thefiring pin is prevented so long as the rubber disc 17 remains in place.

When the cotter pin and pull ring assembly 1 has been withdrawn by theoperator, the grenade is ready for immediate placement. The grenade isthen introduced into a gasoline tank or other receptacle containinggasoline. The gasoline acts upon the rubber disc 17 causing it to swelland then to spring outwardly, thus effectively removing itself from theend of the fuze case 5. At the same time the gasoline will enter througha central hole in the disc 17 and through the holes in the shoulder ofthe perforated plunger 2 and come in contact with the two rubber discs3. The automatic removal of the disc 17 in the manner described permitsthe perforated plunger 2 to be moved upwardly in the fuze case 5 whenthe rubber discs 3 swell under the action of the gasoline on the rubber.

After a period of from four to eight hours the rubber discs 3 willusually have swollen to such an extent as to push the plunger 2 upwardlya distance sufficient to withdraw the retaining ring from around thesplit washer 8. The force of the spring 9 urging the firing pin nut 10and the firing pin 11 in a downward position causes the split washer 8to be forced into the space left by the retaining ring 6. When thishappens, the firing pin is released and the spring 9 forces the firingpin against the primer 16 which sets off the detonator 18 and the TNTcharge 19. The resulting explosion bursts the gasoline container and themagnesium particles, ignited by the explosion, set the gasoline on fire.

While the above described invention is particularly useful in destroyinga tank containing a liquid hydrocarbon, such as gasoline or the like, itmay readily be modified for use in receptacles containing other liquids.

Under such circumstances the disc 17 and the discs 3 acting on theperforated plunger 2 could be made of materials which were capable ofswelling in such other liquids as for example in the case of water,gellatin discs could be used.

We claim:

1. In a time delay fuze having a safety device capable of self armingupon contact with a liquid hydrocarbon the combination of a fuze casehaving a central bore with a cocked firing pin therein, means includinga movable plunger within said bore for releasing the cocked firing pin,and means for preventing premature movement of the plunger to releasethe cocked firing pin, the last mentioned means comprising a rubber disccompressed within the bore at one end adjacent the plunger, said discbeing capable of being deformed upon contact with the liquid hydrocarbonthereby automatically disengaging itself from the bore.

2. A delayed action fuze capable of firing when contacted with a liquidhydrocarbon which comprises a fuze case having a central bore havingpositioned therein a cocked firing pin, a series of discs capable ofbeing deformed upon being contacted with the liquid hydrocarbon, aplunger actuated by the deformation of said discs to release the cockedfiring pin, and means to prevent premature movement of the plunger torelease the firing pin, said means comprising a disc capable of beingdeformed upon contact with the liquid hydrocarbon compressed within thebore at the open end thereof adjacent the plunger thereby permitting thedisc to disengage itself automatically from said bore when contactedwith the liquid hydrocarbon.

3. A delayed action fuze capable of firing when contacted with gasolinewhich comprises a fuze case having a central bore having positionedtherein a cocked firing pin, a series of rubber discs capable of beingdeformed upon being contacted with the gasoline, a plunger actuated bythe deformation of said discs to release the cocked firing pin, andmeans to prevent premature movement of the plunger to release the firingpin, said means comprising a rubber disc capable of being deformed uponcontact with the gasoline compressed within the bore at the open endthereof adjacent the plunger thereby permitting the disc to disengageitself automatically from said bore when contacted with the gasoline.

4. A delayed action fuze capable of firing when contacted for a periodof time with gasoline, which comprises a fuze case having a centralbore, a cocked firing pin positioned within the bore, a split washerengaging with the firing pin in cocked position, a retaining ringholding the split washer in engagement with the firing pin, a movableplunger connected to the retaining ring, a rubber disc capable of beingdeformed upon contact with the gasoline, the said disc being positionedwithin the bore adjacent to the plunger, thereby causing movement of theplunger to release the firing pin when the disc is contacted with thegasoline for a period of time, and means to admit the gasoline to thedisc.

5. In an incendiary grenade adapted to be immersed in a body ofinflammable liquid hydrocarbon and to ignite and scatter the ignitedliquid responsively to detonation of the grenade, the improvement whichconsists in a delayed action fuze mounted on the grenade, the fuzecomprising a casing having a bore extending therethrough andcommunicating with an exterior end recess on the casing, a normallycocked firing pin mounted in the bore, releasable means operativelyconnected to the firing pin securing the latter in cocked position, aspring mounted in the bore and connected to the firing pin continuouslyurging the firing pin towards firing position, a piston mounted in thebore connected to the pin-releasable means and having an enlarged headdirected to the said end recess on the casing, a plurality of rubberdiscs engaging the piston and head thereof, one of the said discs beingpositioned and frictionally held in the end recess on the casing,additional rubber discs being positioned in the bore beneath the pistonhead and in engagement therewith, the said rubber discs being graduallyand progressively deformable while in contact with the said liquidhydrocarbon, the said casing having liquid passages connecting the endrecess with the rubber discs beneath the piston head, the said passagesbeing obstructed by the rubber disc in the end recess until the saiddisc becomes expelled from the recess responsively to deformation of thedisc in contact with the liquid hydrocarbon, the latter then enteringthe passages and contacting the rubber discs beneath the piston head,progressive deformation of these discs under action of the liquidactuating the piston for operating the releasable means for the pins forenabling the pin to snap from cocked position to firing position underaction of the spring responsively to the gradually progressivedeformation of the said rubber discs, and additional removable safetymeans extending into the casing and obstructing the liquid passagesuntil removed, thereby preventing actuation of the firing pin untilafter removal of the safety means from the casing and expulsion of therubber disc from the end recess for uncovering the liquid passages forexposing the discs in the bore to the liquid hydrocarbon.

6. In a time delay fuze capable of firing after immersion in a liquidhydrocarbon for a given period of time, the combination of a casinghaving a bore extending therethrough, a firing pin positioned in thebore, a split washer in the bore adjacent to the firing pin and inengagement therewith for holding the firing pin in cocked position, aretaining ring engaging with the split washer and holding the washer inengagement with the firing pin, a plunger slidably mounted in the boreand opera tively associated with the retaining ring for moving the ringfrom engagement with the split washer, and a series of rubber discscapable of being deformed when immersed in the liquid hydrocarbon, thesaid discs being located in the bore in engagement with the plunger, thediscs being slowly and progressively deformable under prolonged contactWith the liquid hydrocarbon for actuating the plunger after immersion inthe liquid hydrocarbon for a given time until the retaining ring becomesremoved from the split washer, thereby releasing the firing pin.

7. in a time delay fuze capable of firing after immersion in gasolinefor a given period of time, the combination of a housing having a boretherethrough, a firing pin located in the bore, a split washer in thebore and engaging the firing pin for holding the pin in cocked position,a retaining ring engaging the split washer and holding the Washer inengagement with the firing pin, a plunger positioned in the boreconnected to the retaining ring for moving the ring from engagement withthe split washer, and a series of rubber discs operatively engaging theplunger and being protractedly deformable by the gasoline when immersedin the gasoline for a given time until the retaining ring is separatedfrom the split Washer responsively to deformation of the rubber discs bythe gasolines, thereby releasing the firing pin.

8. A delayed action fuze capable of firing when contacted for a periodof time with a liquid hydrocarbon, which comprises a fuze case having acentral bore, a cocked firing pin positioned within the bore, a splitwasher in the bore engaging with the firing pin when the pin is incocked position for securing the pin in the said cocked position, aretaining ring in the bore holding the split Washer in engagement withthe firing pin, a movable plunger in the bore and connected to theretaining ring, and a disc capable of being deformed by prolongedcontact with the liquid hydrocarbon, the disc being positioned in thebore in engagement with the plunger, thereby causing movement of theplunger to release the firing pin when the disc is contacted with theliquid hydrocarbon.

9. A delayed action fuze capable of firing when contacted over aprolonged period of time with a liquid hydrocarbon, which comprises afuze case having a central bore, a cocked firing pin positioned withinthe bore, a split Washer in the bore and engaging with the firing pinwhen the latter is in cocked position, a retaining ring in the boreengaging the split washer for holding the split Washer in engagementwith the firing pin, a movable plunger mounted in the bore and connectedto the retaining ring, a resilient disc positioned in the bore andslowly reactive with the liquid hydrocarbon for gradual deformationresponsively to prolonged contact with the liquid hydrocarbon, the saiddisc being positioned in engagement with the plunger, progressivedeformation of the disc by prolonged contact with the liquid hydrocarboncausing movement of the plunger to release the firing pin and means toadmit the liquid hydrocarbon to the deformable substance.

References Cited in the file of this patent UNITED STATES PATENTS811,252 Seddon Jan. 30, 1906 1,788,856 Bossone Jan. 13, 1931 FOREIGNPATENTS 116,726 Greece Dec. 24, 1900 75,250 Switzerland Oct. 18, 1916495,845 France July 12, 1919

